The site survey checklist that saves quotes from surprises

The quote is not written at the desk. It is written in the twenty minutes you spend in someone's garden with your eyes open. Every surprise you find at survey stage costs a line on a document. Every surprise you miss costs real money, on site, later.

The survey is where the quote is really written

Two builders can price the same drawings and land thousands apart, and the difference is usually not arithmetic, it is observation. One of them saw the Victorian drain run under the proposed footprint and the other did not. The desk work afterwards only prices what the eyes collected, which is why a disciplined survey routine is worth more than any spreadsheet.

The routine below takes twenty to thirty minutes on a typical extension and works as a loop: outside, inside, awkward questions, then photographs of everything. Do it the same way every time, and nothing gets missed because nothing is left to mood.

Outside: access, ground, drains

• Access. Can a skip sit on the drive or does it need a permit? Will a digger fit through the side gate, or is everything coming through the house in buckets? Measure the gap, do not guess it.
• Ground. Slopes mean retaining and steps in foundations. Big trees near the footprint raise root and clay questions. Suspiciously lumpy lawns often mean buried rubble or an old structure. Note anything that hints the dig is not routine, because groundworks is the part of the job you cannot see until the money is committed.
• Drains. Lift every cover you can find. Where do the runs go, how deep, and is anything crossing the proposed footprint? Building over or near public sewers brings the water company into the project, and that is a conversation for now, not for week two.
• The neighbours' side. Attached property, shared access, a flank wall on the boundary: note anything that raises party wall questions early.

Inside: structure, services, finishes

• Structure. Which walls are load bearing? What is above the opening the client wants? Any sag in floors and ceilings, any cracking worth photographing before you become the person who gets blamed for it?
• Services. Boiler age, position and flue route. Consumer unit condition and spare ways. Stop tap location. Gas run. If the extension swallows the room the boiler lives in, that is thousands of pounds hiding in one glance.
• The wet stuff. Signs of damp, condensation history, the state of existing flat roofs. These are extras waiting to be found, and they are cheaper to find now.
• Finishes at the joint. Where new meets old, what happens? Matching floor levels, plaster junctions, skirting profiles. "Making good" is a real cost that lump-sum quotes forget.

One habit ties the inside loop together: open things. The loft hatch, the cupboard under the stairs, the panel behind the bath if the client will let you. The expensive surprises live behind the surfaces nobody looked behind, and "can I stick my head in the loft?" costs nothing but a minute and a torch.

The awkward questions to ask while you are there

The survey is also the last cheap moment to ask the questions that shape the price. Who is supplying the kitchen? Are you living here through the works? What is the real budget ceiling? The full set is in questions to ask a client before you price anything, and the answers belong in the same notebook as the drain depths.

The checklist, on one page

From survey to price without losing anything

The last discipline is transfer: everything observed has to reach the quote, or the survey was tourism. Write the survey up the same day, while the smells and squeaks are fresh, into three buckets: facts (measurements, positions, conditions), risks (things that need an assumption or exclusion), and decisions still needed from the client. Those buckets map directly onto the sections of a professional document, as laid out in what a professional builder's quote should include.

This is also where a good tool pays for itself. Give QS Quoter the written-up survey as a job description, or the drawings alongside it, and it produces an itemised quote at your own rates with the risks you spotted framed as assumptions, plus a private tradesman copy holding your real numbers. The surprises you caught in the garden become lines on a document, which is exactly where surprises belong.